Emrooz challenges Iranian conservatives
Iran's judiciary has ordered one of two main pro-reformist websites to be "filtered", making it unavailable to internet subscribers in Iran.
The Emrooz website was set up by people close to Iran's reformist President, Mohammad Khatami.
Since a crackdown on reformist press, the internet has become the main forum for dissident voices in Iran.
But with elections approaching, it is feared the judiciary's move may signal a new wave of political repression.
Emrooz carries news and current affairs articles that are broadly sympathetic to the reformist agenda, and challenge the wide-ranging powers of Iran's spiritual leader, Ayatollah Ali Khamenei.
Ayatollah Khamenei controls some of Iran's most powerful non-elected institutions, including the judiciary and the army.
The judiciary has closed down more than 90 newspapers in the past five years, and many of these responded by opening their own websites and continuing to publish online.
Individual writers also embraced new technology to write their own personal news diaries, known as weblogs or blogs.
Now it seems the judiciary may be turning its attention to these new websites.
The website was set up by supporters of President Khatami
Iranian internet service providers have always been prevented from permitting access to sites deemed pornographic or anti-Islamic by the authorities, most of which originate outside Iran.
But this is the first time the judiciary has banned an Iran-based domestic political website in this way.
Internet access in Iran is simple to arrange and affordable for most middle class families.
Some seven million Iranians have access to the internet - that is one in 10 of the population, and double the number two years ago.
In Iran's highly restricted media environment, the internet has until now been a way for writers and the reading public to get around the barriers of censorship.
Now it seems the Islamic authorities may be trying to bring new media under the same tight controls as the press.